parameters card

Dear Sarah,

First,
> h3 > h2 z $z,
means that any z propagator within the h3 > h2 z should be offhsell.
The final Z is on the otherhand going to be onshell.
Since this is a 1> 2 process, they are no propagator inside that 1> 2 process and therefore the "$z" is meaningless.

So your syntax is the same as
> q q~ > h3 , ( h3 > h2 z, ( z > l+ l- ))

if you want the Z that decays into lepton to be offshell you need to use the following syntax:
> q q~ > h3 , ( h3 > h2 l+ l- $ Z)

> then I launched the process and I edited the para card ( I changed the masses of z to be less than 90 GeV also I changed the values of all Higgs masses ( mh3 = 190, mh+-=659,mh1 = 585)

In the standard model (and many model) you have the gauge invariance that links various parameter together.
In the case of the standard model one of the following parameter is given analytically by the other three
MZ, MW, a_ew, Gf
The default choice for many mode is to compute MW based on the other three. I guess that this is the case for your model as well.

In the (standard Model) computation of MW, you do have a square root and the argument of the square root is not definite positive. Meaning that for some choice of parameter of MZ, a_ew, Gf, it is possible that such argument is negative and therefore that the mass of the W boson is for your benchmark a complex number.

This is what is happening in your model as well according to this error.
> Exception : Mass should be real number: particle 24 (w+) has mass: (48.167504873841224+13.978445152860093j)

Cheers,

Olivier

> On 14 Oct 2021, at 12:41, Sarah <email address hidden> wrote:
>
> New question #699095 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/699095
>
> Good morning
> I generated the process q q~ > h3 , ( h3 > h2 z $z, ( z > l+ l- ))
> where $z means the z boson is off shell particle and (h3 the cp odd Higgs, h2 is the sm Higgs =125 )
>
> then I launched the process and I edited the para card ( I changed the masses of z to be less than 90 GeV also I changed the values of all Higgs masses ( mh3 = 190, mh+-=659,mh1 = 585)
>
> after I made this editing I launched the process again but it shows me this message
>
> Command "generate_events run_04" interrupted with error:
> Exception : Mass should be real number: particle 24 (w+) has mass: (48.167504873841224+13.978445152860093j)
> Please report this bug on https://bugs.launchpad.net/mg5amcnlo
> More information is found in 'ME5_debug'.
> Please attach this file to your report.
>
>
> Can you help ?
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

thank you Olivier, I would not know how to generate the process without your help.

for mw , should I change its value depending on the mass of z? since z is off shell (its mass should be less than 90 GeV)

Hi,

The value in the param_card is the pole mass.

A propagator is by definition a virtual particle which might (or not ) be onshell meaning that virtuality of the propagator paricle (p^2) can be different (or equal) to the pole mass.

So the fact that your z is offshell does not mean that you have to change the mass of the Z in the param_card.
so if with this syntax:
generate q q~ > h3 , h3 > h2 l+ l-

you are asking h3 to be onshell (up to multiple times the width)
h2 to be exactly onshell (assymptoticly free state)
no requirement on Z (I guess this force it to be offshell due to h3/h2 mass gap)

Cheers,

Olivier

PS: Please discuss such point with your supervisor

> On 14 Oct 2021, at 14:10, Sarah <email address hidden> wrote:
>
> Question #699095 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/699095
>
> Sarah posted a new comment:
> thank you Olivier, I would not know how to generate the process without
> your help.
>
> for mw , should I change its value depending on the mass of z? since z
> is off shell (its mass should be less than 90 GeV)
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Thank you Olivier for your time. I appreciate you

I did generate generate q q~ > h3 , ( h3 > h2 e+ e- $z) and I got the cross section for different values of Higgs bosons masses.

Now I am trying to generate the same process but from gloun (g).

First I imported 2HDM model then I use the generate function but it says it is unveiled process. can you help me with that?

Best regards

MG5_aMC>display multiparticles
Multiparticle labels:
p = g u c d s u~ c~ d~ s~
j = g u c d s u~ c~ d~ s~
l+ = e+ mu+
l- = e- mu-
vl = ve vm vt
vl~ = ve~ vm~ vt~
all = g u c d s u~ c~ d~ s~ a ve vm vt e- mu- ta- ve~ vm~ vt~ e+ mu+ ta+ t b t~ b~ z w+ h+ h1 h2 h3 w- h-
MG5_aMC>generate g g > h3 , ( h3 > h2 e+ e- )
INFO: Checking for minimal orders which gives processes.
INFO: Please specify coupling orders to bypass this step.
INFO: Trying process: g g > h3 WEIGHTED<=2 @1
Command "generate g g > h3 , ( h3 > h2 e+ e- )" interrupted with error:
NoDiagramException : No amplitudes generated from process Process: g g > h3 WEIGHTED=2 @1
   Decay: h3 > h2 e+ e-. Please enter a valid process
MG5_aMC>

This likely means that the model did not have any interaction (at tree level at least) between g g h3.
and therefore that model can not be used to generate that process.

I guess here you can use a NLO model to use the loop-induced mode for generating
g g > h3 [QCD]
but decay will be problematic, if the h3 width is small then you can use the method described/introduced in the loop induced paper.

Cheers,

Olivier

I see
I tried to generated it in 2HDM NLO but I couldn't.